The imaging of complex cellular structures is central to modern cancer biology, and a state-of-the-art Microscopy Facility is essential to the mission of a Cancer Center. As such, the Wistar Institute has made a strong effort to acquire the necessary instrumentation to accomplish its mission and to have it managed by a highly competent biological imaging specialist, Mr. James Hayden. The Microscopy Facility has served an important role for the members of the Wistar Cancer Center since 1973. Over the past five years, the Facility has grown tremendously and, with changes in scientific focus and the addition of new technologies and instrumentation, has evolved into a premier asset of the Institute and Cancer Center. With new leadership, a reconfiguration of space that improved utilization, new technical applications, new support services, and training at all levels, the Facility has experienced a substantial increase in Cancer Center member usage. Since 2003, thirty-one out of 32 laboratories from all three Cancer Center research programs have used services provided by the Microscopy Facility. Significant scientific accomplishments published in high impact journals have been achieved using new facility equipment, including the Xenogen MS imaging system for in vivo bioluminescent studies of tumor metastases (Huang, Kissil and Pure), the 2 Photon microscopy system to image in vivo movement of immune cells and their interaction with tumor cells (Ertl and Weninger laboratories), and the Live-Cell microscopy system to image in-vitro cell-cell and cell-matrix interactions (M. Herlyn, Heber-Katz, and Pure laboratories). Standard wide-field and confocal microscopy (Lieberman, Maul and Rauscher laboratories) available through the Facility has also aided studies in molecular interactions at the subcellular level. Since the previous renewal, approximately $514,000 was committed by the Institute for new instrumentation and upgrades.